There are lights which use a solid-state light source such as a laser. In such lights, white light is created by irradiating phosphor with blue light emitted by the solid-state light source. The phosphor causes yellow light resulting from excitation by one part of the blue light and the other part of the blue light that is transmitted to disperse, thereby enabling the production of white light obtained through the mixing of these lights.
On the other hand, solid-state lighting sources such as a laser have strong directionality and high energy density. As such, when phosphor is directly irradiated with the blue light emitted by a solid-state light source, the region of the phosphor which is irradiated generates much heat and becomes hot. Since phosphor has a thermal quenching property in which wavelength conversion efficiency deteriorates with increasing temperature, it is necessary to suppress the rise in temperature of the phosphor.
In view of this, for example, Patent Literature 1 discloses a lighting apparatus in which a diffusion means which diffuses light from a solid-state light source is formed on a phosphor layer. According to Patent Literature 1, the diffusion means diffuses the energy distribution of the light from the solid-state light source, to thereby prevent concentration of energy (reduce the thermal load) on the phosphor layer and suppress rising of the temperature of the phosphor layer.